Driver side airbag modules are designed to be attached to a center portion of a steering wheel armature. The armature or skeleton portion of the steering wheel includes two or more spokes which are attached to a circular rim. Often the rim and spokes are encapsulated with foam having an outer skin of polyurethane, simulating leather, or covered in leather. Optional wood or wood simulation can adorn the steering wheel. Typically incorporated into these steering wheels can be a variety of devices or switches that operate the cruise control or the horn or the radio, to name a few. Centered in the steering wheel is situated the airbag module for protecting the driver of the vehicle.
This driver side airbag module assembly is securely attached to the armature. It is often referred to as the DAB module (driver airbag module) assembly and it includes an inflator and an airbag cushion located inside a module housing which has an outer cover concealing the cushion. This outer cover often has a frangible tear seam that allows the inflating airbag to break the seam and deploy upon inflation. Often the entire DAB module includes or overlays one or more horn activation switches. To sound the horn, the driver pushes on the cover of the DAB module and the entire DAB assembly is moved inwardly, closing the contacts of the underlying horn activation switches, causing the horn to blow or sound.
To assemble the DAB module assembly to a steering wheel has been, at best, a challenge. Ideally, to insure a secure attachment that is reliable and rather simple to achieve, manufacturers have strived to develop snap-in driver side airbag modules. The goal has been to connect the airbag module electrically and then snap the entire assembly into locking engagement with the steering wheel. Once attached, these devices generally require special tools to unlatch and replace the module, as it may be necessary to replace it once deployed or in case it becomes inoperable.
A large challenge in the use of snap-in modules is to have the cover equally spaced on assembly such that the gaps along the edges of the cover and the steering wheel are substantially equal. If the module snaps into position and the gaps are unequal, this is readily noticeable and very unappealing. On horn activated DAB modules, the problem can occur as the driver activates the horn, so even if the module is centered on assembly it can be shifted by sounding the horn. To overcome this, airbag modules have been made with complex designs to limit lateral movement. U.S. Pat. No. 7,398,994 B2 “A Snap-In Assembly For Retaining An Airbag Module To A Steering Wheel” discloses a retaining assembly to drive an airbag module that is moveable linearly exclusively along a path parallel to the axis of rotation of the steering wheel while providing constant horn activation loads. This retention assembly is a masterful design which limits the movement of the module exclusively in a linear direction regardless of the location on which the driver presses on the airbag cover. This prior art design, while very effective, requires a complex design.
Naturally, if the airbag module is fixed and rigidly secured to the steering wheel then the horn activation must occur differently. One way to accomplish this is to allow the horn switches to be positioned under the airbag cover and have only the cover moveable so the horn switches can be activated by depressing only the cover; these devices are often referred to as floating horns.
The assembly of the airbag module is somewhat more simplified in that the housing can be directly and rigidly affixed to the hub of the steering wheel. Nevertheless, a module that snaps into place upon assembly is preferred.
In view of above, assembly of steering wheels provided with traditional assemblies for installing airbag modules, which also are to activate the vehicle horn, is often time consuming and expensive.
The present invention also provides a retaining assembly for airbag modules, in particular a snap-in retaining assembly, which permits in-line assembly of an airbag module in a steering wheel in an easy and quick way.
It is an object of the present invention to provide a snap-in DAB module assembly, but with a much simpler design.
These and other beneficial objectives are achieved by the present invention as described herein.